The Dhammika Sutta is part of the Sutta Nipata(Sn 2.14). In this sutta, the Buddha instructs a lay disciple named Dhammika on rules for monks and on the "layman's rule[s] of conduct" (gahatthavatta).
Dhammika Sutta Wikipedia
In the sutta, Dhammika, along with 500 other lay followers (Pali: pancahi upasake-satehi), approaches the Buddha and his monks (Pali: bhikkhavo) and Dhammika asks the Buddha how should a disciple (Pali: sāvako) be virtuous (Pali: sādhu) — both a disciple who has gone from home to homeless (Pali: agārā anagārameti) and a disciple from a household (Pali: agārino ... panupāsakāse). Dhammika then proceeds to extol the Buddha's compassion and wisdom.
In response to Dhammika's question, the Buddha first addresses his monks and advises them as follows:do alms rounds at the appropriate time
be rid of interest in the five senses
return from alms rounds, sit alone and turn inward
do not slander or blame others or seek out disputation
care for your food, dwelling and robes but do not become attached to them
The Buddha notes that a householder's obligations prevent a householder from fully pursuing a monk's path. Thus, the Buddha articulates "the layman's duty" (Pali: gahatthavatta), what are essentially the Five Precepts, as follows:Do not kill or hurt living things or incite others to kill
Avoid taking what is not given or inciting others to do so
Observe celibacy or at least do not have sex with another's wife
Do not lie or incite others to lie
Do not drink or incite others to drink intoxicants
For the Uposatha, the Buddha extols the practice of the Eight Precepts, which involve the aforementioned Five Precepts (with celibacy alone identified for the third precept) and the following three precepts added:Do not eat at inappropriate times (traditionally meaning, one meal before noon)
Do not wear garlands or perfumes
Sleep at floor level
The Buddha further stated that, when celebrating the Uposatha, with a purified heart (Pali: pasanna citto) and rejoicing mind (Pali: anumodamāno), the wise (Pali: viññu) share their food and drink with monks of the Sangha.
In the sutta's last verse, the Buddha advises that, if a lay person supports their parents and engages in fair trading, they will be reborn among self-radiant devas.